I was just looking at the concept art on the lucasarts page, and i saw (possible spoiler)

a wookie destroying a battle droid. after that i looked at the pictures at gamespot and there was another concept art showing a wookie walking along the clone troopers. has there been any mention of wookies being in the game and possibly working with you (and maybe even playable characters, at least in multiplayer)

Well the wookie home planet of kashyyyk is in the game and in the description on the lucasarts official site trandoshan slavers are in the game and they usually enslave wookies. so liberating and fighting with wookies is a good possibility.